What sentences will help me find out the purpose of "Thank You, Ma'am?

To find the purpose of the short story “Thank You, Ma’am” by Langston Hughes look for sentences in which Mrs. Luella Bates Washington Jones lets the young man know that she is going to teach him something or shows him that she trusts him. For example, when she refuses to let him go after he runs into her and attempts to steal her purse she says,

But you put yourself in contact with me,” said...

To find the purpose of the short story “Thank You, Ma’am” by Langston Hughes look for sentences in which Mrs. Luella Bates Washington Jones lets the young man know that she is going to teach him something or shows him that she trusts him. For example, when she refuses to let him go after he runs into her and attempts to steal her purse she says,

But you put yourself in contact with me,” said the woman. “If you think that that contact is not going to last awhile, you got another thought coming. When I get through with you, sir, you are going to remember Mrs. Luella Bates Washington Jones.

At that point in the story, he is not sure what she is going to do with him, but she is not going to let him go.

When she takes him back to her room, she determines the reason he tried to steal her purse through a series of questions before instructing him to get washed up and get ready to have a good meal. She confides in him that she did things in the past in order to let him know she understands his situation. At no time did she try to embarrass or mistrust him and made unquestioning small talk with him while they ate.

After the shared dinner, she gives him the money to buy the shoes he wanted imploring him to behave.  

Now, here, take this ten dollars and buy yourself some blue suede shoes. And next time, do not make the mistake of latching onto my pocketbook nor nobody else’s—because shoes come by devilish like that will burn your feet. I got to get my rest now. But I wish you would behave yourself, son, from here on in.